Turbine bucket having axially extending groove

ABSTRACT

A turbine bucket and corresponding turbines are disclosed herein. In one aspect, the turbine bucket includes: a blade member; and a base member affixed to the blade member, the base member configured to attach to a turbine rotor radially inward of the blade member, wherein the base member includes a first semi-elliptical extension spanning substantially an axial length of the base member and extending at least partially perpendicularly in relation to a primary axis of the turbine bucket.

BACKGROUND OF THE INVENTION

The subject matter disclosed herein relates to a turbine bucket andrelated turbines. Specifically, the subject matter disclosed hereinrelates to a turbine bucket base (or, shank) including a semi-ellipticalchannel configured to provide axial fluid flow of a cooling fluidthrough a turbine.

Some power plant systems, for example certain nuclear, simple cycle andcombined cycle power plant systems, employ turbines to drive generatorsand generate electricity. Some of these turbines (e.g., steam turbines)are driven by a flow of high temperature steam which is directed throughsets of stationary nozzles (or, vanes) and across the face of turbineblades, forcing rotation of those blades along with the turbine rotor.This high temperature steam can negatively affect certain components inthe turbine, such as a drum rotor. Prolonged exposure of the drum rotorto high-temperature steam may result in inefficient operation,corrosion, system damage, and a need for rotor repairs and/or rotorreplacement.

Some systems attempt to counteract the aforementioned affects caused byhigh-temperature steam by forming the turbine rotor of more resilientmaterials. However, introducing these more resilient materials into theturbine rotor formation may increase overall costs. Additionally, thesematerials may add complexity to the turbine design and manufacturingprocess.

BRIEF DESCRIPTION OF THE INVENTION

A turbine bucket and corresponding turbines are disclosed herein. In oneaspect, the turbine bucket includes: a blade member; and a base memberaffixed to the blade member, the base member configured to attach to aturbine rotor radially inward of the blade member, wherein the basemember includes a first semi-elliptical groove spanning substantially anaxial length of the base member.

A first aspect of the invention includes a turbine bucket having: ablade member; and a base member affixed to the blade member, the basemember configured to attach to a turbine rotor radially inward of theblade member, wherein the base member includes a first semi-ellipticalgroove spanning substantially an axial length of the base member.

A second aspect of the invention includes a turbine having: a stator; adiaphragm at least partially housed within the stator; and a rotorsubstantially surrounded by the diaphragm, the rotor including: aturbine bucket having: a blade member; and a base member affixed to theblade member, the base member attached to the rotor radially inward ofthe blade member, wherein the base member includes a firstsemi-elliptical groove spanning substantially an axial length of thebase member.

A third aspect of the invention includes a turbine having: a statorincluding a cooling path extending therethrough; and a rotorsubstantially surrounded by the stator and fluidly connected with thecooling path, the rotor including: a plurality of turbine buckets, eachof the plurality of turbine buckets having: a blade member; and a basemember affixed to the blade member, the base member attached to therotor radially inward of the blade member, wherein the base memberincludes a pressure-side semi-elliptical groove spanning substantiallyan axial length of the base member, the pressure-side semi-ellipticalgroove interacting with a suction-side semi-elliptical groove in anadjacent one of the plurality of turbine buckets to form a fluid conduitextending axially along the blade member.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features of this invention will be more readilyunderstood from the following detailed description of the variousaspects of the invention taken in conjunction with the accompanyingdrawings that depict various embodiments of the invention, in which:

FIG. 1 shows a close-up three-dimensional perspective view of a turbinebucket according to embodiments of the invention.

FIG. 2 shows a three-dimensional end view of a plurality of turbinebuckets, aligned in a partially circumferential manner, according toembodiments of the invention

FIG. 3 shows a cut-away view of a portion of a turbine according toembodiments of the invention.

It is noted that the drawings of the invention are not necessarily toscale. The drawings are intended to depict only typical aspects of theinvention, and therefore should not be considered as limiting the scopeof the invention. In the drawings, like numbering represents likeelements between the drawings.

DETAILED DESCRIPTION OF THE INVENTION

Aspects of the invention provide for a turbine bucket. Specifically,aspects of the invention disclosed herein relate to a turbine bucketbase (or, shank) having a semi-elliptical channel configured to provideaxial fluid flow of a cooling fluid through a turbine.

As noted herein, some turbine designers have attempted to counteract thedetrimental affects caused by high-temperature steam on turbine rotorcomponents by forming the turbine rotor of more resilient materials.However, introducing these more resilient materials into the turbinerotor formation may increase overall costs. Additionally, thesematerials may add complexity to the turbine design and manufacturingprocess.

In contrast to conventional approaches, aspects of the invention involveintroducing a cooling circuit including an axial fluid flow passage in aturbine to allow for cooling of turbine components (e.g., rotorcomponents). In particular, aspects of the invention include a turbinebucket having a semi-elliptical groove configured to allow for axialfluid flow of a cooling fluid through portions of a turbine rotor inorder to cool the rotor (e.g., the drum).

Turning to FIG. 1, a close-up three-dimensional perspective view of aturbine bucket 2 is shown according to embodiments of the invention. Inone aspect of the invention, the turbine bucket 2 includes: a blademember 4; and a base member 6 affixed to the blade member 4. The basemember 6 and the blade member 4 may be affixed to one another viaconventional means, e.g., via welding, brazing or other conventionalmeans of adhesion. It is understood that base member 6 and blade member4 may be formed substantially of a metal (e.g., steel), and may beformed separately (e.g., via separate casting and/or forging methods),or collectively (e.g., as integrally fabricated members). In any case,the blade member 4 and base member 6 may be affixed, and in use, thebase member 6 is configured to interact with a slot in a turbine rotor(not shown in this view). The base member 6 is configured to attach tothe turbine rotor radially inward of the blade member (indicated bydirectional arrow “r”), using its dove-tail shape, denoted bydovetail-shaped portions 8. The interaction between the dovetail-shapedportions 8 of the turbine bucket 2 will be further explained herein withrespect to the additional figures.

Also illustrated in FIG. 1, the base member 6 includes a firstsemi-elliptical groove 10 spanning substantially an axial length (L) ofthe base member. In one embodiment, the first semi-elliptical groove 10may span an axial length L of the base member, excluding the axiallengths of the dovetail-shaped portions 8. As will be further describedand illustrated herein, where the first semi-elliptical groove 10 spanssubstantially the axial length L of the base member 6, and whenconfigured to interact with adjacent semi-elliptical grooves (furtherdescribed herein), it may aid in providing an effective axial fluidconduit, as part of a of a cooling circuit providing coolant axiallydownstream through the rotor. As shown, the first semi-elliptical groove10 may define a segment 12 of the base 6 extending at least partiallyperpendicularly in relation to a primary axis (a_(b)) of the turbinebucket 2 (where the primary axis (a_(b)) of the turbine bucket 2 issubstantially aligned with the radial axis (r). In some embodiments, thefirst semi-elliptical groove 10 may have a major arc radius (r_(a)) ofapproximately 0.08 inches to approximately 0.1 inches. It is understoodthat the major arc radius will be limited by the thickness of the basemember 6 forming the semi-elliptical groove 10. As is described furtherherein, the major arc radius (r_(a)) of the first semi-elliptical groove10 can be distinct from the minor arc radius (r_(b)) of the secondsemi-elliptical groove 14, where, as the name implies, the minor arcradius (r_(b)) is less than the major arc radius (r_(a)). That is, thepressure side of the turbine bucket 2 can include a semi-ellipticalgroove having a distinct arc radius from an arc radius of the suctionside of the turbine bucket 2. Additionally, it is understood that eachrespective arc radius (major and/or minor) may be substantiallynon-uniform across the axial length L of the base member 6. That is, insome embodiments, one or more of the arc radii (r_(a)) or (r_(b)) canvary across the axial length L, such that the groove 10 appears todiverge or converge from an axial perspective view. In some cases,adjacent base members 6 can have adjacent grooves that have convergingor diverging radii, which may be coupled to form converging or divergingchannels, respectively.

In an alternative embodiment, a groove may be formed in the base member6 of a distinct shape from the semi-elliptical design shown. Forexample, designs employing angles (e.g., partial hexagonal, octagonal,diamond-shaped, etc.) may also be used to form a portion of anaxially-extending channel as described herein. It is understood thatthese alternative embodiments will likely involve increased stressforces proximate the grooves, as the ellipse configuration is designedto bear greater stress. In any case, the design of base member 6 may beconfigured to interact with a complementary base member 6 having agroove structure configured to at least partially form an axiallyextending cooling channel.

As shown in FIG. 1, the base member 6 may further include a secondsemi-elliptical groove 14 spanning substantially the axial length L ofthe base member. This second semi-elliptical groove 14 may extend in anopposite direction from the base member 6 as the first semi-ellipticalgroove 10. For example, where aligned in a turbine (shown herein), thefirst semi-elliptical groove 10 may be on a pressure side 11 of the basemember 6, while the second semi-elliptical groove 14 may be on acircumferentially suction side 15 of the base member 6. When aligned asa plurality of substantially similar base members 6, the leading groove10 of a first base member 6 may interact with the pressure-side groove14 of an adjacent base member 6 to form a channel (FIG. 2), andsubstantially fluidly seal a portion of that channel from the blademember 4.

In some embodiment, the first semi-elliptical groove 10 (and in somecases, the second semi-elliptical groove 14) may be formed of asubstantially identical composition as the remainder of the base member6. For example, in some cases, both the base member 6 and the grooves10, 14 may be formed substantially of steel, e.g., martensitic stainlesssteel. It is understood that some aspects of the invention may allow forthe use of relatively lower-cost materials when compared withconventional rotor base members, as the base members (e.g., base member6) shown and described herein experience increased cooling due to theirgrooved design, when compared with conventional rotor base members. Insome embodiments, the base member 6 and grooves 10, 14 may be integrallyfabricated. In one case, the base member 6 and the grooves 10, 14 may beintegrally cast or forged. In another case, the base member 6 and thegrooves 10, 14 may be machined (e.g., cut) from one or more adjoinedpieces of material (e.g., steel). It is understood that additionalembodiments are also possible in view of the various aspects of theinvention described herein, and that in some cases portions of thegrooves 10, 14 (e.g., segment 12 and a corresponding segment on groove14) may be formed separately from the base member 6 and later adjoined(e.g., via welding, brazing, etc.).

Turning to FIG. 2, a three-dimensional end view of a plurality ofturbine buckets 2, aligned in a partially circumferential manner, isshown according to embodiments of the invention. As shown, the pluralityof turbine buckets 2 are arranged substantially circumferentially aboutan axis (a, into the page) of a turbine rotor (rotor omitted in thisview). As is also evident in FIG. 2, adjacent turbine buckets 2, and inparticular, adjacent semi-elliptical grooves 10 may form a portion of afluid circuit (e.g., a cooling circuit) 16 configured to receive acooling fluid, as is further explained herein. It is understood that insome embodiments, adjacent sets of leading grooves and trailing grooves(e.g., first semi-elliptical groove 10 and second semi-elliptical groove14) may be joined (either simply by contact and compression forces, orvia welding, brazing or other adhering means) to form a portion of thefluid circuit 16.

Turning to FIG. 3, a cut-away view of a portion of a turbine 20 includesa stator 22 at least partially housing a diaphragm 24, including aplurality of static nozzle stages 26 (having nozzle vanes 28). As isknown in the art, a working fluid (e.g., steam) is fed (e.g., from asteam source, not shown) across the faces of the nozzle vanes 28, whichthereby direct the working fluid across the blade members 4 of eachturbine stage 30, respectively. As is known in the art, the diaphragm 24substantially surrounds a rotor 32, the rotor having a plurality ofdovetail slots 34 for receiving the dovetail-shaped portions 8 of thebase member 6. As is also known in the art, the rotor 32 may rotateabout its central axis (a), driven by the flow of the working fluidacross the blade members 4 coupled thereto (by respective base members6). Also visible in the turbine 20 of FIG. 3 are the semi-ellipticalgrooves 10, which may help to define a portion of a cooling path 36(whereby the cooling path extends across an axial length of a portion ofthe rotor 32). That is, each of these semi-elliptical grooves 10 mayspan an axial length (along the “a” axis) of respective base members 6,thereby guiding the flow of fluid axially along the turbine rotor 32.

The cooling path 36 may extend from an inlet 38 in the turbine 20, to aportion of the rotor 32, whereby it passes radially inward of the blademembers 4. The cooling path 36 may be partially defined in part bymembers (indicated by letters “E” and “F”) extending axially fromaxially facing sides of the base member 6 and/or nozzle stages 26 (at adiaphragm ring segment). The cooling path 36 may be further defined,according to aspects of the invention, by the semi-elliptical grooves 10spanning an axial length of the base members 6. This portion of thecooling path 36 is indicated in areas by the letter “G”, whichcorresponds to portions of the cooling path 36 extending betweenopenings in circumferentially adjacent base members 6 (arranged instages 30). As described herein, use of these semi-elliptical grooves 10may substantially fluidly seal the blade members 4 from the coolingcircuit 36. That is, the semi-elliptical grooves 10 may substantiallyfluidly isolate working portions of the turbine (e.g., those areas wherethe working fluid flows therethrough) from the cooling path 36. Thesesemi-elliptical grooves 10 may aid in providing an effective coolingpath 36, thereby maintaining a desired temperature of the rotor 32. Insome cases, the cooling fluid (e.g., steam) passing through the coolingpath 36 may have a temperature of at least approximately 200 degreesFahrenheit less than the temperature of the working fluid. It isunderstood that as the cooling fluid travels axially through theturbine, its temperature will increase, and may approach the temperatureof the working fluid.

It is understood that aspects of the invention provide forconfigurations of a portion of a cooling circuit through a turbine rotor(e.g., a rotor drum). The teachings described herein may be combinedwith other teachings (e.g., the use of axially extending members fromaxially facing portions of base member 6) to complete an effectivecooling path 36 which isolates the working fluid of the turbine from thecooling fluid. As noted, in some embodiments, the “grooves” describedherein may be formed of a variety of shapes sufficient to substantiallyfluidly isolate portions of the cooling path (e.g., cooling path 36)from the blade members (e.g., blade member 4). Use of the coolingpath(s) described herein may allow for construction of a turbine (e.g.,turbine 20) using less heat-resistant materials, when compared with someconventional turbines.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting of the disclosure.As used herein, the singular forms “a”, “an” and “the” are intended toinclude the plural forms as well, unless the context clearly indicatesotherwise. It will be further understood that the terms “comprises”and/or “comprising,” when used in this specification, specify thepresence of stated features, integers, steps, operations, elements,and/or components, but do not preclude the presence or addition of oneor more other features, integers, steps, operations, elements,components, and/or groups thereof.

This written description uses examples to disclose the invention,including the best mode, and also to enable any person skilled in theart to practice the invention, including making and using any devices orsystems and performing any incorporated methods. The patentable scope ofthe invention is defined by the claims, and may include other examplesthat occur to those skilled in the art. Such other examples are intendedto be within the scope of the claims if they have structural elementsthat do not differ from the literal language of the claims, or if theyinclude equivalent structural elements with insubstantial differencesfrom the literal languages of the claims.

1. A turbine bucket comprising: a blade member; and a base memberaffixed to the blade member, the base member configured to attach to aturbine rotor radially inward of the blade member, wherein the basemember includes a first semi-elliptical groove spanning substantially anaxial length of the base member.
 2. The turbine bucket of claim 1,wherein the base member includes a dovetail shape configured to interactwith a dovetail opening in the turbine rotor.
 3. The turbine bucket ofclaim 1, wherein the first semi-elliptical groove has an arc radiusbetween approximately 0.08 inches and approximately 0.1 inches.
 4. Theturbine bucket of claim 1, wherein the first semi-elliptical groove hasa non-uniform arc radius across the axial length of the base member. 5.The turbine bucket of claim 1, wherein the first semi-elliptical groovehas a first arc radius and is formed on a pressure side of the basemember, and further comprising a second semi-elliptical groove having asecond arc radius smaller than the first arc radius, wherein the secondsemi-elliptical groove is formed on a suction side of the base member.6. The turbine bucket of claim 1, further comprising: a secondsemi-elliptical groove spanning substantially the axial length of thebase member, wherein the first semi-elliptical groove and the secondsemi-elliptical groove define portions of the base member extending atleast partially perpendicularly from a primary axis of the turbine inopposite directions from the base member, and wherein the firstsemi-elliptical groove has a larger arc radius than an arc radius of thesecond semi-elliptical groove.
 7. The turbine bucket of claim 1, whereinthe first semi-elliptical groove is configured to interact with a secondsemi-elliptical groove of an adjacent turbine bucket to substantiallyform a channel.
 8. A turbine comprising: a stator; a diaphragm at leastpartially housed within the stator; and a rotor substantially surroundedby the diaphragm, the rotor including: a turbine bucket having: a blademember; and a base member affixed to the blade member, the base memberattached to the rotor radially inward of the blade member, wherein thebase member includes a first semi-elliptical groove spanningsubstantially an axial length of the base member.
 9. The turbine ofclaim 8, wherein the base member includes a dovetail shape configured tointeract with a dovetail opening in the turbine rotor.
 10. The turbineof claim 8, wherein the first semi-elliptical groove has an arc radiusof approximately between approximately 0.08 inches and approximately 0.1inches.
 11. The turbine of claim 8, wherein the first semi-ellipticalgroove has a non-uniform arc radius across the axial length of the basemember.
 12. The turbine of claim 8, wherein the first semi-ellipticalgroove has a first arc radius and is formed on a pressure side of thebase member, and further comprising a second semi-elliptical groovehaving a second arc radius smaller than the first arc radius, whereinthe second semi-elliptical groove is formed on a suction side of thebase member.
 13. The turbine of claim 8, further comprising: a secondsemi-elliptical groove spanning substantially the axial length of thebase member, wherein the first semi-elliptical groove and the secondsemi-elliptical groove define portions of the base member extending atleast partially perpendicularly from a primary axis of the turbine inopposite directions from the base member.
 14. The turbine of claim 8,wherein the first semi-elliptical groove is configured to interact witha second semi-elliptical groove of an adjacent turbine bucket tosubstantially form a seal.
 15. The turbine of claim 8, wherein the rotorfurther includes a plurality of turbine buckets arrangedcircumferentially about an axis of the rotor, each of the plurality ofturbine buckets including a semi-elliptical groove configured tointeract with a complementary semi-elliptical groove of an adjacentturbine bucket among the plurality of turbine buckets.
 16. The turbineof claim 8, wherein the primary axis of the turbine bucket extendssubstantially perpendicularly from a central axis of the turbine.
 17. Aturbine comprising: a stator having a cooling path extendingtherethrough; and a rotor substantially surrounded by the stator andfluidly connected with the cooling path, the rotor including: aplurality of turbine buckets, each of the plurality of turbine bucketshaving: a blade member; and a base member affixed to the blade member,the base member attached to the rotor radially inward of the blademember, wherein the base member includes a pressure-side semi-ellipticalgroove spanning substantially an axial length of the base member, thepressure-side semi-elliptical groove interacting with a suction-sidesemi-elliptical groove in an adjacent one of the plurality of turbinebuckets to form a fluid conduit extending axially along the blademember.
 18. The turbine of claim 17, wherein the primary axis of theturbine bucket extends substantially perpendicularly from a central axisof the rotor.
 19. The turbine of claim 17, wherein the pressure-sidesemi-elliptical groove is forged or cut with a remainder of the basemember.
 20. The turbine of claim 17, wherein the pressure sidesemi-elliptical groove has a distinct arc radius from the suction-sidesemi-elliptical groove of the adjacent one of the plurality of turbinebuckets.